It can take off (at 35km/h) at night when it is calm and can climb to 8500m during the day as it stores solar energy. During the night it descends to 1500m to save power.
Two pilots, Bertrand Piccard and Andre Borschberg, will take turns flying the plane for alternating legs of the journey for each of the five- to six-day stints at the controls.
The 3.8 cubic metre cockpit - which is unpressurised - has also been adapted so the pilots can spend so long up in the air.
There is oxygen for high-altitude flight and the seat reclines to double as a bed, so the pilots can rest, and there is space to exercise. There is also a toilet built in.
It is estimated the pilots will face temperatures as high as 40C and low as -40C and the project website says they will use self-hypnosis and meditation techniques to maintain focus.
Nutritionists estimate the pilots will need 2.4kg of food, 2.5 litres of water and 1 litre of sports drink a day during the long legs of the solar flight.
Stops include Muscat, Oman; Ahmedabad and Varanasi, India; Mandalay, Burma; and Chongqing and Nanjing, China. After crossing the Pacific Ocean via Hawaii, the plane will fly across the United States, stopping in Phoenix, New York City and a Midwest location to be decided.
After crossing the Atlantic, the final legs include a stop-over in Southern Europe or North Africa before arriving back in Abu Dhabi.
Piccard is described as a doctor, psychiatrist, explorer and aeronaut who made the first non-stop round-the-world balloon flight, and is the Solar Impulse founder and chairman.
Borschberg is an engineer and graduate of the Massachusetts Institute of Technology (MIT) in management science, a trained fighter pilot and professional aeroplane and helicopter pilot.
The flight is to showcase how innovation and clean technologies can change the world - but solar-powered commercial flight is a long way off.
Airbus says that while solar energy may be able to help a small aircraft fly, it is unlikely to be a practical solution for enabling larger, commercial airliners into the sky.
"The technology might take a giant leap forward with future advances; but today, even if an entire aircraft was covered with the most efficient solar panels available, this still would not be enough to propel it," it said.
For the more immediate future, solar power could provide electricity aboard airliners once they reach cruise altitude, or help with ground operations at airports.
